This application proposes to extend ongoing investigations in the Framingham Offspring Study which is examining biological and behavioral risk factors for bone loss and related fractures to include measures of serum osteocalcin (total and degree of carboxylation) and plasma vitamin K (phylloquinone) concentrations to assess the influence of vitamin K status on BMD. Plasma 25-hydroxyvitamin D also will be assayed to evaluate whether the relationship between vitamin K status and bone health is influenced by vitamin D status. These biochemical measurements will be compared to BMD measurements of the spine and hip collected at the 6th consecutive physical examination. From the Original Framingham Cohort of 3800 participants, 2000 males and females, ages 28-84 years will be studied. Covariates in addition to 25(OH) D concentrations include: age, anthropometric data, physical activity, medication use, smoking and diet including energy, protein, calcium, alcohol, and caffeine. The proposed studies will identify factors that lead to bone loss and help clarify the role of vitamin K status in the development of osteoporosis. Results of the studies proposed could lead to effective intervention programs that reduce bone loss resulting in a decreased risk and incidence of osteoporosis.